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Author Topic:   Remote Electrical Fuel Tank Level Gauge
masbama posted 08-17-2011 10:31 AM ET (US)   Profile for masbama   Send Email to masbama  
[The remote electrical fuel tank level] gauge [on a 1999 Boston Whaler DAUNTLESS 18 boat] reads FULL all the time. I don't think [the cause of this problem is] the gauge, because [the gauge] turns off when I shut down the electrical [power]. When I have the motor running [the electrically operated remote fuel tank level gauge] shows FULL all the time. Is this a simple fix?
jimh posted 08-17-2011 08:08 PM ET (US)     Profile for jimh  Send Email to jimh     
Yes.
masbama posted 08-17-2011 09:13 PM ET (US)     Profile for masbama  Send Email to masbama     
Well, would you mind sharing your knowledge on how to fix it?
contender posted 08-17-2011 10:14 PM ET (US)     Profile for contender  Send Email to contender     
Most chances it is the sender--11 years old. I have had to replace two senders, now on my third. in my fuel tank.
meridian posted 08-17-2011 10:22 PM ET (US)     Profile for meridian  Send Email to meridian     
The sender can be easily checked with an ohmmeter. I replaced mine with a unit from WEMA for $50.
jimh posted 08-17-2011 10:48 PM ET (US)     Profile for jimh  Send Email to jimh     
Find the sender. Check the circuit. Here are some options for senders:

http://continuouswave.com/ubb/Forum6/HTML/000632.html

jimh posted 08-18-2011 08:03 AM ET (US)     Profile for jimh  Send Email to jimh     
Most electric fuel gauges use a standarized resistive sender. The sender resistance varies in proportion to tank level. A current passes though the gauge and the sender. The gauge indicates tank level in proportion to the current flowing through the sender. There are only four elements in the circuit:

--the source of the current, usually the battery via some sort of secondary power distribution through the engine, and via an ignition key switch;

--the meter

--the sender

--the wires that connect the devices

You can generally test the meter by connecting to battery negative the pole of the meter that normally connects to the sender [but insert a series resistor of about 33-ohm to protect the meter movement]. This should cause the meter to read full scale, typically.

The sender can be checked by disconnecting all wiring to it and measuring its resistance.

The wires that connect the devices can be checked for continuity and shorts.

The source of the current can be checked with a multimeter.

masbama posted 08-18-2011 09:46 AM ET (US)     Profile for masbama  Send Email to masbama     
Thanks! I will check the system. It is interesting to know that an electrical current is being sent to a sender that close to gasoline.
jimh posted 08-19-2011 09:45 PM ET (US)     Profile for jimh  Send Email to jimh     
Please note that I emended my comments about testing the meter by grounding the sensor lead. Usually a meter is somewhat resilient and can tolerate a bit of current overload, but just to be sure, you should use a resistor when testing.
masbama posted 04-23-2012 06:42 PM ET (US)     Profile for masbama  Send Email to masbama     
I called Whaler today [i.e., eight months after the discussion began] and spoke to Chuck. He said [the remote electric fuel tank level sender that is thought to be the cause of the problem with the constant FULL-level indication in the 1999 Boston Whaler DAUNTLESS 18 boat] is a WEMA sender, 9-inch model. Are [fuel tank tank level sensors] easy to replace? Thinking of doing it myself but I don't want to get blown up.
Whalrman posted 04-23-2012 08:36 PM ET (US)     Profile for Whalrman  Send Email to Whalrman     
Interestingly [the fuel tank gauge on my boat] is doing the same, showing FULL all the time. Will have to dig into this to see whats with it. Boat is a 1999 Outrage 18 with a 91-gallon tank made by Florida Marine Tank.
masbama posted 04-23-2012 10:51 PM ET (US)     Profile for masbama  Send Email to masbama     
Let me know what you do. Thanks.
L H G posted 04-24-2012 01:52 AM ET (US)     Profile for L H G    
A fuel gauge that reads full constantly needs a new sender, unless wiring is defective.
jimh posted 04-24-2012 06:29 AM ET (US)     Profile for jimh  Send Email to jimh     
The replacement of the fuel tank level sensor most likely involves just the removal of the sensor from the tank top. Most sensors are mechanically fastened to the fuel tank top with six or more threaded fasteners. A rubber gasket is used to provide a seal. To service the fuel tank level sensor you will need sufficient clearance above the tank top to be able to withdraw the sensor. In boats made by Boston Whaler I would expect that sufficient clearance would be provided.

Since the fuel tank will likely contain gasoline and gasoline vapor, the service of the tank level sender must be performed in a manner that does not generate any electrical sparking and away from any source of combustion. Also be careful not to drop anything into the tank while working with the sensor removed.

jimh posted 04-24-2012 08:01 AM ET (US)     Profile for jimh  Send Email to jimh     
By the way, how did you determine the cause of the problem to be the sender? The discussion has jumped from the diagnostic phase to the repair phase, but we did not hear how the sender was found to be defective.
masbama posted 04-24-2012 09:25 AM ET (US)     Profile for masbama  Send Email to masbama     
My mechanic [investigated the cause of the problem] and deemed the sender defective; the gauge [is] OK.

I checked the WEMA website but I could find [no WEMA fuel tank level sender] that look like [the fuel tank level sender in the boat]. [My fuel tank level sender] is metal with a wire attached to a post in the center, another wire attached to a plug on the top of the sender and another wire that is attached to a screw that holds the sender to the tank and to a screw that holds the fuel intake to the hull.

tmann45 posted 04-24-2012 01:29 PM ET (US)     Profile for tmann45  Send Email to tmann45     
Those electrical connections don't sound like a WEMA fuel level sensor, they sound like the conventional float on an arm rotating rheostat-type. I also thought the WEMA magnetically coupled "digital" type would be very long lived. I've just replaced my original Teleflex type from 1996 with a WEMA. I'll have to remember to update this post in 16 years.
Whalrman posted 04-24-2012 08:18 PM ET (US)     Profile for Whalrman  Send Email to Whalrman     
Today I got into [the repair of a different boat, not the boat initially under discussion] and found that the Rochester [fuel tank level] sender was good. [I] removed and cleaned the mechanical parts and replaced the gasket. As for the sender, I found that the wire for the negative circuit at the gauge was off the lug. The [fuel tank level] gauge reads as it should now; thankfully, [the repair] was this easy.
jimh posted 04-24-2012 10:17 PM ET (US)     Profile for jimh  Send Email to jimh     
You mention the "WEMA website." What is the URL for that website?
tmann45 posted 04-24-2012 10:47 PM ET (US)     Profile for tmann45  Send Email to tmann45     
http://www.wemausa.com/
masbama posted 04-24-2012 11:57 PM ET (US)     Profile for masbama  Send Email to masbama     
I don't think mine is a WEMA like Chuck told me. It looks like a Moeller like the ones on their website. I guess I'll have to take it oot to find out.

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